"It is not a wise choice!"، this was the reaction of my father when I applied for nuclear medicine residency program 26 years ago. The old retired officer continued that hi-tech nuclear medicine is dependent on multiple advanced sections that may not be easily available especially in the developing countries. Now he is not alive to see that political misconducts have added fuel to the fire.Global shortage of Technetium-99m in recent years revealed the vulnerability of nuclear medicine and dependency of our clinical departments on the policies of the governments to support production of radiotracers (1). Although the mission of International Atomic Energy Agency (IAEA) is to "accelerate and enlarge the contribution of atomic energy to peace، health، and prosperity throughout the world"، its application is highly affected by local governmental policies (2)Recent unilateral withdrawal of USA from Iran nuclear deal (Joint Comprehensive Plan Of Action-JCPOA) followed by imposing economic، trade and financial sanctions against Iran، has deleterious effect on nuclear medicine either on supply of radiotracers or spare parts of nuclear medicine devices (3). Although medicine is apparently not included in the list of sanctions، secondary sanction، aviation and transport embargo as well as financial restrictions، made it extremely difficult for medical companies to be able to do any transaction. Payment for the drugs or instruments and shipment of the goods to and from Iran have turned to a lengthy، difficult and risky task. Nuclear medicine seems to be at particular risk due to its link with atomic energy agency.

We aim to investigate the clinical impact of 18F-FDG PET/CT in managing patients with gynecological malignancies and pelvic or extrapelvic lymph nodes that are of equivocal significance on conventional imaging.

Methods

We retrospectively evaluated 18F-FDG PET/CT scans of patients with gynecologic tumors who were referred to King Hussein Cancer Center from January 2010 to August 2014. PET/CT results were compared with MRI and CT findings. We evaluated sensitivity and specificity of 18F-FDG PET/CT، its role in changing treatment plan and its positive predictive value (PPV) and negative predictive value (NPV).

18F-FDG PET/CT has high clinical impact in management of gynaecological cancers as it alters the treatment plan in a substantial number of patients who had equivocal findings on conventional imaging، as well as it offers excellent validity in lymph nodes staging.

To investigate the diagnostic accuracy of positron emission mammography (PEM) and positron emission tomography/computed tomography (PET/CT) for small breast tumors of less than 20 mm in size.

Methods

The study was conducted on a total of 100 subjects (i.e.، 50 patients with pathologically proven breast cancer and 50 normal cases of medical screening). The total number of tumors was 54 (mean size: 11±5.1 mm، range:4-20 mm). The diagnostic accuracy of PEM alone، PET/CT alone، and combined PET/CT and PEM was evaluated by two nuclear medicine physicians based on visual inspection. The two groups (i.e.، tumors of ≤ 10 mm and > 10-20 mm) were compared in terms of the diagnostic capability of the three modalities (PEM alone، PET/CT alone، and PET/CT+PEM).

Results

The sensitivities of PEM alone، PET/CT alone، and combined PET/CT and PEM were 72%، 60%، and 76%، respectively. The specificities of these tests were 98%، 100%، and 98%، respectively. Furthermore، the accuracies of these diagnostic modalities were 85%، 79%، and 87%، respectively. The combined PET/CT and PEM showed significantly higher sensitivity and accuracy than PET/CT alone (P=0.005 and P=0.02، respectively). In addition، PEM demonstrated a significantly higher sensitivity than PET/CT in the ≤ 10 mm group (P=0.03); however، no difference was observed between the two modalities in the > 10 mm group in terms of sensitivity.

Conclusion

18F-fluorodeoxyglucose PET had limited capability for the detection of small breast cancers of < 10 mm. Combined PET/CT and PEM showed higher sensitivity and accuracy، compared to PET/CT alone.

To evaluate the role of Tc-99m TRODAT-1 Single Photon Emission Computed Tomography (SPECT) in Parkinson’s Disease (PD) by assessing the correlation of clinical disease severity، disease duration and age at onset of disease with specific uptake ratio of Tc-99m TRODAT-1 in striatum.

Methods

The study included 63 patients in age range of 40-72 years with clinical diagnosis of PD and nine controls. Clinical history of patients was obtained regarding age at onset of disease and disease duration. Disease severity in each patient was assessed using H and Y stage and UPDRS. Tc-99m TRODAT-1 SPECT was performed and specific uptake ratios were calculated for six regions in bilateral striata، caudate nuclei and putamina. Difference in specific uptake ratios between different stages of disease was analyzed for statistical significance. Specific uptake ratios were correlated with UPDRS، motor score of UPDRS، duration of disease and age at onset of disease using Pearson’s correlation co-efficient.

Results

Median specific uptake ratio was found to be least in contralateral putamen for all H and Y stages. There was a statistically significant difference between specific uptake ratios of controls vs stage 1، stage 1 vs 2، 1 vs 3، 1 vs 4، and 2 vs 4 for all 6 regions. The difference in uptake ratio between 3 and 4 H and Y stages was significant only for contralateral regions. There was no significant difference in uptake ratio between 2 and 3 H and Y stages. The uptake ratios showed a strong negative correlation with UPDRS and motor score، a weak negative correlation with duration of disease and no significant correlation with age at onset of disease.

Conclusion

We conclude that Tc-99m TRODAT-1 SPECT can be used to assess the disease severity in PD patients.

Positron emission tomography/computed tomography (PET/CT) examination is commonly used for the evaluation of pulmonary nodules since it provides both anatomical and functional information. However، given the dependence of this evaluation on physician’s subjective judgment، the results could be variable. The purpose of this study was to develop an automated scheme for the classification of pulmonary nodules using early and delayed phase PET/ CT and conventional CT images.

Methods

We analysed 36 early and delayed phase PET/CT images in patients who underwent both PET/CT scan and lung biopsy، following bronchoscopy. In addition، conventional CT images at maximal inspiration were analysed. The images consisted of 18 malignant and 18 benign nodules. For the classification scheme، 25 types of shape and functional features were first calculated from the images. The random forest algorithm، which is a machine learning technique، was used for classification.

Results

The evaluation of the characteristic features and classification accuracy was accomplished using collected images. There was a significant difference between the characteristic features of benign and malignant nodules with regard to standardised uptake value and texture. In terms of classification performance، 94.4% of the malignant nodules were identified correctly assuming that 72.2% of the benign nodules were diagnosed accurately. The accuracy rate of benign nodule detection by means of CT plus two-phase PET images was 44.4% and 11.1% higher than those obtained by CT images alone and CT plus early phase PET images، respectively.

Conclusion

Based on the findings، the proposed method may be useful to improve the accuracy of malignancy analysis.

Renography is used for the diagnostic evaluation of pediatric patients with a suspected obstruction of urinary tract or impaired renal function. The recommended dose for children have been released by the European Association of Nuclear Medicine، Society of Nuclear Medicine and Molecular Imaging، and Japanese Society of Nuclear Medicine. Since acquisition counts in dynamic scintigraphy are affected by the administered doses and sensitivity of the scintillation camera، the scan procedure should be determined independently. In this study، we constructed simplified dynamic phantom imitating pediatric renography and tested its performance.

Methods

Simplified dynamic phantom consisted of three components (i.e.،infusion، imitated kidney، and drainage sections). The infusion rates (mL/min) were determined by comparing the time activity curves obtained from patients with normal renal function. The time-points of the maximum counts (Tmax)، as well as the two-thirds and one-half of the maximum counts (T2/3 and T1/2) were measured in different doses using the phantom with the best-match infusion rate and duration، and low-energy general-purpose (LEGP) or low-energy highresolution (LEHR) collimators and applying different attenuations.

Results

The best-match infusion rates of the phantom to imitate the time activity curve of the normal renal function were 42.0، 1.0، 0.6، and 0.3 mL/min in the arterial، secretory، early-excretory، and late-excretory phases، respectively. When 30 MBq، LEHR collimator and non-water-equivalent phantom were applied، Tmax، T2/3، and T1/2 were 242±15.3، 220±10.0 and 317±25.2 seconds، respectively. Using LEGP collimator and (3 MBq of activity) 5-cm water-equivalent phantom، Tmax، T2/3، and T1/2 values were estimated as 242±5.8، 213±11.5، and 310±17.3 sec، respectively.

Conclusion

Our simplified dynamic phantom for pediatric renography could imitate the time activity curves obtained from patients with normal renal function. Tmax، T2/3، and T1/2 could be measured under various settings of dose،collimator، and tissue attenuation.

The latest single-photon emission computed tomography (SPECT)/computed tomography (CT) reconstruction system، referred to as xSPECT Bone™، is a context-specific reconstruction system utilizing tissue segmentation information from CT data، which is called a zone map. The aim of this study was to evaluate the effects of zone-map enhancement incorporated into the ordered-subset conjugated gradient minimization (OSCGM) reconstruction method on SPECT images.

Methods

Image quality with zone-map enhanced OSCGM (OSCGMz) and nonenhanced OSCGM methods was compared using various reconstruction parameters. The compartment phantom had 3 radioactive sections with CT values of about 1000، 250، and 0 HU. SPECT data were acquired using a lowenergy high-resolution (LEHR) collimator، with a 256×256 matrix and 2.4-mm pixel size. The performances of the 2 reconstruction methods (OSCGM vs.OSCGMz) were evaluated on the basis of %error، coefficient of variation (%CV)، and normalized mean squared error (NMSE)، and adequate iterative update numbers were determined. The relative CV representing the ratio of smoothed images to non-smoothed images was calculated to evaluate the effects of the Gaussian filter on each section set with different CT values.

Results

On comparing the OSCGM and OSCGMz methods، it was found that the %error of the OSCGMz method tended to show convergence with fewer updates، especially in the high CT value section mimicking bone absorption. In the water section، the %CV of the OSCGMz method was lower than that of the OSCGM method. The NMSE minimum values for the OSCGM and OSCGMz methods were obtained at 30 and 20 updates، respectively. The relative CV for the OSCGMz method in the water section decreased remarkably according to the size of the full width at half maximum (FWHM) of the Gaussian filter.

Conclusion

The zone-map enhancement contributed to SPECT reconstruction for the reproduction of radioactive concentrations in bone tissues، using a low number of OSCGM updates. Our findings indicated that the incorporation of zone maps into SPECT reconstruction might improve image quality.

Alternative normalization methods were proposed to solve the biased information of SPM in the study of neurodegenerative disease. The objective of this study was to determine the most suitable count normalization method for SPM analysis of a neurodegenerative disease based on the results of different count normalization methods applied on a prepared digital phantom similar to one obtained using fluorodeoxyglucose-positron emission tomography (FDG-PET) data of a brain with a known neurodegenerative condition.

Methods

Digital brain phantoms، mimicking mild and intermediate neurodegenerative disease conditions، were prepared from the FDG-PET data of 11 healthy subjects. SPM analysis was performed on these simulations using different count normalization methods.

Results

In the slight-decrease phantom simulation، the Yakushev method correctly visualized wider areas of slightly decreased metabolism with the smallest artifacts of increased metabolism. Other count normalization methods were unable to identify this slightly decreases and produced more artifacts. The intermediate-decreased areas were well visualized by all methods. The areas surrounding the grey matter with the slight decreases were not visualized with the GM and VOI count normalization methods but with the Andersson. The Yakushev method well visualized these areas. Artifacts were present in all methods. When the number of reference area extraction was increased، the Andersson method better-captured the areas with decreased metabolism and reduced the artifacts of increased metabolism. In the Yakushev method، increasing the threshold for the reference area extraction reduced such artifacts.

Conclusion

The Yakushev method is the most suitable count normalization method for the SPM analysis of neurodegenerative disease.

The purpose of this research is to study the effect of beta spectrum on absorbed fraction ( ) and to find suitable analytical functions for beta spectrum absorbed fractions in spherical and ellipsoidal volumes with a uniform distribution for several radionuclides that are commonly used in nuclear medicine.

Methods

In order to obtain the beta particle absorbed fraction، Monte Carlo simulations were performed by using the MCNPX code. The validation of the simulations was performed by calculating the absorbed fractions in spheres and comparing the results with the data published by other investigators. The absorbed fractions were calculated and compared by using an actual beta energy spectrum with those obtained through the mean beta energy of 14C، 199Au، 177Lu، 131I، 90Sr، 153Sm، 186Re، 32P، 90Y، 38Cl and 88Rb radionuclides.

Results

The maximum difference between the absorbed fractions for beta particles accounting for the whole beta spectrum of all the considered nuclides was 29.62% with respect to the mean beta energy case. Suitable analytical relationships were found between the absorbed fraction and the generalized radius، and the dependence of the fitting parameters from beta spectrum energy was discussed and fitted by appropriate parametric functions.

Conclusion

The results allowed the calculation of the absorbed fractions from the above stated beta sources uniformly distributed in spherical and ellipsoidal volumes of any ellipticity and volume، in a wide range of practical volumes that are not only used for internal dosimetry in nuclear medicine applications، but also in radiological protection estimates of doses from internal contamination.

Granulocyte colony-stimulating factor (G-CSF) is a hematopoietic cytokine which controls the differentiation and growth of hematopoietic cells in the bone marrow. We report a severe aplastic anemia (SAA) patient with false-negative 99mTc sodium phytate bone marrow imaging findings under concurrent G-CSF therapy. The first bone marrow imaging showed a normal bone marrow activity. However، the bone marrow biopsy pathology report revealed a lack of hematopoietic cells. Furthermore، the complete blood count indicated severe pancytopenia resulting in the diagnosis of aplastic anemia (AA). A second marrow scan implemented after the stoppage of G-CSF showed an abnormal bone marrow activity، which matched the pathology reports. Accordingly، the concurrent administration of G-CSF was considered as the cause of false-negative bone marrow imaging findings obtained in the first scan. Consequently، it should be kept in mind that a 99mTc sodium phytate bone marrow scintigraphy during the concurrent administration of G-CSF may lead to the achievement of false negative results because it induces changes in bone marrow mimicking a normal marrow scan in patients with AA.

Colorectal carcinoma is one of the most common causes of cancer-related death، worldwide. Recently، due to the introduction of novel imaging and therapeutic techniques، five-year survival of patients has increased. However، distant metastasis is still expected in half of the patients. Colorectal cancer tends to target the abdominal cavity، liver، lungs، and bones as the common sites of metastasis. Nevertheless، rare cases of muscle metastasis have been reported. This report presents a 23-year-old male، who despite chemotherapy، demonstrated gradual progressive disease and metastases to the submandibular region، lungs، adrenal gland as well as muscles and subcutaneous tissues. He had developed multiple asymptomatic muscular metastases metachronously over two-year time period discovered on an 18FDGPET/CT، namely in the deltoid، external oblique abdominis، rectus abdominis، and quadriceps muscles، as well as one of the extrinsic muscles of the tongue. The presence of distant، especially extrahepatic metastasis، adversely affects the prognosis of colon carcinoma. Since limited cases of muscle metastasis have been reported in carcinoma of colon، the underlying pathophysiology، optimum treatment، and prognostic issues are yet to be substantiated.

FDG PET CT scan is considered to be a sensitive tool to detect skeletal metastasis in known malignancies. However، it’s high sensitivity and low specificity may account for false positive diagnosis in cases of trauma، infection، inflammation and other benign conditions. Skeletal hemangioma is one of the common benign conditions which are typically ametabolic on FDG PET CT with no uptake on bone scan. However، rarely they may have atypical imaging features and appear hypermetabolic. Other imaging modalities such as MRI and CT scan have typical imaging findings for hemangioma and can be used for evaluation of focal hypermetabolic skeletal lesions. There are atypical imaging characteristics in each of these modalities. Hence when used judiciously they can complement each other and avoid a false positive test result. This case report highlights the importance of bone scan and CT scan in excluding pathological involvement of skeleton with false positive FDG PET scan results.

We reported a 71 years old woman، with history of rest and postural tremor، bradykinesia and memory problems. In her dynamic MRI، a contrastenhanced tumor in the cerebellopontine (CP) angle was found which was compatible with a meningioma. 99mTc-TRODAT SPECT showed decreased activity in the left putamen، indicating idiopathic Parkinson disease. There was also a focus of increased activity on the right side of the skull base، which was compatible with meningioma in MRI.

This series comprises of a quiz pertaining to the identification of salient and important anatomical structures and landmarks expected to be seen at a given level on the computed tomography (CT) image. The representative image is followed by a series of images showing examples of different commonly encountered pathological entities that can be seen at this level in a routine clinical practice. Readers are encouraged to identify highlighted anatomical structures and landmarks in all the images and appreciate how a given abnormality can alter the appearance of normal structures. It is expected that this series will help nuclear physicians in interpretation of the CT component of the single photon emission computed tomography (SPECT) and positron emission tomography (PET) studies.